RE Topology Report

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About the RE Topology Report

The RE Topology Report visualizes the Research & Education routing topology that converges on Internet2's AS11537. It's built from a snapshot of every BGP route received by Internet2 from its eBGP neighbors — pre-policy, so you see what neighbors announce, not just what Internet2 chose to install. Both accepted routes (those that passed Internet2's import policy and ROV) and rejected routes (those that violated policy and were filtered) are kept and labelled, so you can see the full set of paths neighbors offer to Internet2 and where filtering happens.

The data

• BGP routes — a snapshot of every pre-policy route received by Internet2 (AS11537) on each of its eBGP sessions. Each route carries a prefix, an AS-path, and a flag indicating whether Internet2's import policy accepted or rejected it. Consecutive duplicate ASes in the AS-path (path-prepending) are collapsed before aggregation.
• AS organization names — CAIDA's as-org2info dataset, refreshed every 24h. Provides the friendly operator name shown next to each AS number (e.g. AS3356 — Level 3 Parent, LLC).
• RIPE Stat fallback — for ASes that CAIDA's join doesn't cover (LACNIC and AFRINIC coverage in the CAIDA dataset is historically spotty), the report queries RIPE Stat's as-overview and whois endpoints and uses the resulting holder string. RIPE Stat aggregates whois from every RIR.
• Prefix holder names — RIPE Stat whois with an ARIN RDAP fallback chain (rdap-bottom → /registry/ip/), used to populate the holder column in the per-AS prefix lists. Lookups are cached at 24h ± 4h so repeat builds don't re-hit the upstream services.

The tree (front page)

The front page is a hierarchical tree of every AS that appears in any AS-path Internet2 received. The root is AS11537; its direct children are Internet2's eBGP neighbors; their children are the next AS in those neighbors' paths; and so on down to the origin AS that announced each prefix.

• Click the ▶ toggle on a row to expand its sub-tree; click again to collapse.
• Click the AS pill (the AS… — name chip) to open the focused Sankey panel for that AS.
• The four numeric columns (right-aligned, alternating background) show, for the AS at that tree position:
  • Accepted — count of distinct prefixes whose path traverses this AS and that Internet2 accepted into its forwarding table.
  • Rejected — count of distinct prefixes whose path traverses this AS but that Internet2 rejected (RPKI invalid, ASPA invalid, IRR mismatch, etc.).
  • Paths to — number of distinct tree-paths whose terminal AS is this one (paths originating here). Click the highlighted multi-path cell to open the Sankey panel and see them at once.
  • Paths through — number of distinct tree-paths that traverse this AS. Always ≥ Paths to: a path ending at the AS also passes through it; the difference is paths heading to a more-distant origin in this AS's customer cone. Click the highlighted value to open that upstream topology.
• Tooltip on each numeric cell adds the originated count when the AS is itself the origin (e.g. “1,243 accepted prefixes through AS3356 (12 originated here)”).

The Sankey panel (focused mini-DAG)

Clicking an AS opens a side panel with a layered Sankey diagram of every distinct AS-path the focused AS uses to reach AS11537. The diagram is a Sugiyama-style DAG — left-to-right layering, dummy nodes inserted on long edges so ribbons stay monotonic and crossings are minimised by a barycenter sweep.

• The focused AS sits on the left (orange) and AS11537 on the right (blue, with a fixed minimum height so the accepted/rejected split is always readable). Every intermediate AS sits in its own column between them.
• Ribbon thickness at any cross-section is proportional to the number of prefixes flowing through that edge.
• Color identifies the last-hop AS into AS11537 — that is, the Internet2 neighbor that handed the route over. Every ribbon along a single end-to-end path keeps the same colour so you can trace it visually.
• AS11537's bar is split into an accepted band (top, blue) and a rejected band (bottom, black). Band heights are sized by prefix-flow deliveries across paths, and the label inside each band also shows the unique-prefix count.
• Inside each band, prefixes group into blocks by signature: prefixes announced via the same set of upstream ASes (or paths, for rejected) form one block at a fixed y-offset. Strands from different sources to the same block target the same y, so shared prefixes overlap visually as multiple coloured ribbons stacked at one point. That's the one-glance multi-path indicator at the destination.
• Hover any ribbon to see the from→to ASNs, source AS, prefix count, and (for shared blocks) which other ASes carry the same prefixes. Click an AS bar to open a route-table modal listing every prefix that flows through it, with holder names and full AS-paths.
• The panel can be resized by dragging its left gutter; width is persisted in localStorage. The Show all routes upstream toggle expands the view from "routes that originate at this AS" to "every route in this AS's customer cone seen by Internet2".
• The URL hash #asn=NNN[&upstream=0] tracks the focused view, so any panel state is a shareable link.

Search

The search box accepts an AS number (AS27343 or just 27343), a partial AS name, an IP address, or a prefix (192.0.2.0/24). IPs and prefixes are matched with longest-prefix match against every announced prefix in the report, so you can drop in any IPv4 or IPv6 address and jump to the AS that originates its covering prefix. Activating a result opens the Sankey panel for that AS.

Attribution

This tool is part of the ROOTBEER (Routing Operations Observational Technology: Building to Enable Education and Research) suite, a joint effort between Internet2 and CAIDA (the Center for Applied Internet Data Analysis at UC San Diego). Internet2 contributes the BGP route snapshots and operational policy context; CAIDA contributes the AS-organization, AS-relationship, and topology datasets that power the rest of the suite.

This material is based on research sponsored by the National Science Foundation (NSF) grant OAC-2530871. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of NSF.

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Data sources — freshness

Each row below shows when this report's view of that upstream feed was last refreshed. The BGP-route fetch runs once at process startup; per-session entries older than 72 hours are evicted from the on-disk cache.

Source	Last refreshed	Items	Notes